Inasmuch as many drums are stored in warehouses and shipped and transported in many ways both domestically and internationally, the shape and cubical size of such drums, become increasingly important because storage and shipping charges are normally based not only on the cubical contents of the drum, but the space it consumes for such pruposes. When storing and shipping large quantities of such drums, it will be readily apparent that very small reduction in cubicity of the space requirement of any one particular drum will make a relatively large difference in the overall volume consumed and the additional charge required therefore.
In the locking rim assembly disclosed in commonly assigned U.S. Pat. No. 3,039,666, the hinge and locking lever means for the split rim sections are practically dead center on opposed sides of the drum. First of all, experience has proven that this arrangement rendered it difficult at times to open the split rim to remove the closure from the drum. Towards this end, movement of one of the sections about the hinge in the horizontal direction would bring it into tighter engagement with the associated chime surfaces as it is pivoted past the adjacent corner. Needless to say, the construction and disposition of this locking rim assembly added to the cubicity requirements of the drum.
Heretofore it was extremely difficult if not impossible to fabricate a satisfactory bead in a plain fiber shell without any reinforcement because the fiber possesses memory and tends to gradually return to the shape from which it came, and is subject to flexing and crushing when drums are stacked one on on top of another. Experience has proven in rough handling, particularly if such a drum falls off a truck or is roughly tipped over in routine use or abuse, with a relatively shallow bead in the top of the drum, even if reinforced with metal, the cover and the rim will most likely separate from the drum because the coupling or latching affect of the rim in the bead is ineffectual because of the fact that the bead is shallow.
Over the years it has definitely been proven that a sufficiently deep bead is absolutely necessary particularly for the shape of drum contemplated by this invention to assure that the locking rim assembly is held securely under all types of rough commercial handling, thereby maintaining the drum cover in place to secure and seal the contents of the drum therein. Towards this end, drums according to this invention, having transversely convex sides connected by rounded corners, require deep and metal reinforced beads. However, numerous difficulties were encountered in beading the corners of the chime strips for the drums because of the tremendous amount of contraction required to form the metal around the corners. In the event a very shallow bead was present, this would not be much of a problem (i.e., contracting the metal around the corner, but then the drum would not be effectual or much good for commercial use).